I agree with this from experience. I also agree with Skunk about keeping the PC around just in case.

But if you must sell: Before selling a computer, I always keep the hard drive and place it in a enclosure in case I need to refer back to it. Cloning software is good, but having originals of anything is always a plus. Buy a cheap, used HDD to replace the one inside the laptop.

If the laptop isn't worth the trouble of replacing the hard drive or isn't worth a lot on money, consider keeping it and find something else to sell or a cheaper computer to buy.